A test handler is used in the semiconductor industry for testing operational characteristics of electronic devices, such as light-emitting diodes (LEDs) or other integrated circuit (IC) packages. For instance, the test handler may test and classify LEDs into different grades according to their emitted light intensity, colour, etc. Specifically, the test handler comprises a testing apparatus for testing characteristics of electronic devices, an input module (e.g. a vibratory feeder) for transferring the electronic devices towards the testing apparatus, and a suction pickup device for transferring the electronic devices successively from the input module to the testing apparatus. The feeder typically includes a linear track along which the electronic devices are conveyed and lined up as the feeder vibrates. The feeder also includes a cover arranged over the linear track for retaining the electronic devices within the feeder during operation. In particular, the cover includes an opening through which the electronic devices are successively picked up by the suction pickup device from the feeder to the testing apparatus.
One problem encountered by conventional test handlers relates to adjacent electronic devices overlapping onto each other. FIG. 1a illustrates side and top views of a conventional electronic package 100, which comprises a main body 102 and electrical leads 104 extending from the main body 102. FIG. 1b illustrates the conventional electronic packages 100 being conveyed along a linear track 106 of a vibratory feeder. As the electronic packages 100 are being conveyed along the linear track 106 of the vibratory feeder, the electrical leads 104 of adjacent electronic packages 100 may mount onto each other. Such a phenomenon is known as “piggybacking”. FIG. 1b also shows the feeder comprising a cover 108 that is arranged over the linear track 106, wherein a suction pickup device 110 of the test handler would not be able to pick up the electronic package 100 due to such piggybacking. Thus, it is necessary to separate the first two leading electronic packages 100 before the suction pickup device 110 picks up respective electronic packages 100 from the feeder to the testing apparatus.
A conventional input module for transferring electronic packages is shown in FIG. 2, which comprises a vibratory feeder 200 having a linear track 201 with first and second vacuum passages 202a, 202b and a track end sensor 204 (hidden from view by the leading electronic package) arranged at the end of the linear track 201. As the feeder 200 vibrates, the electronic packages are lined up and conveyed along the linear track 201. Upon the leading electronic package being detected by the track end sensor 204, the first vacuum passage 202a is activated to create a vacuum force beneath the leading electronic package. This holds the leading electronic package in place on the linear track 201 as it awaits pickup by a suction pickup device 206. At the same time, the second vacuum passage 202b is also activated to create a vacuum force beneath its adjacent electronic package to hold it in place on the linear track 201. As the suction pickup device 206 moves downward to pick up the leading electronic package from the feeder 200, the first vacuum passage 202a is deactivated to remove the vacuum force beneath the leading electronic package 100 so that a suction force from the suction device 206 holds the leading electronic package and transfers it from the feeder 200 to a testing apparatus for testing.
However, a drawback of the conventional input module of FIG. 2 is that there is no mechanism that creates a gap between the leading and adjacent electronic package to prevent piggybacking. Moreover, the time lag in the removal of the vacuum forces created by the first and second vacuum passages 202a, 202b. In particular, if a residual vacuum force from the first vacuum passage 202a remains after the first vacuum passage 202a is deactivated, the suction force from the suction device 206 may not be strong enough to overcome the residual vacuum force to effectively transfer the leading electronic package from the feeder 200 to the testing apparatus unless a sufficiently long pick delay time is used to ensure the residual vacuum force has dissipated.
Thus, it is an object of the present invention to seek to propose a transfer apparatus for transferring electronic packages that addresses the drawbacks of the conventional apparatus, and to provide the public with a useful choice.